Why is the evening Mysore class 2 1/2 hours long?
Once you know the approximate length of your practice you can show up in class at any point within that 150 minute time frame. There is no strict starting time except what is convenient to you unless your teacher has given you a specific time to come. For example if your practice is 1 hour long you can show up anytime between 5:30PM and 7:00PM so that you have enough time to finish.